1. Field of the Invention
The present invention relates to a dielectric waveguide filter with cross-coupling and a multi-layered resonator structure within multiple layers using a via and a pattern, and more particularly, to a dielectric waveguide filter used in a millimeterwave radio frequency (RF) front-end module of a 60 GHz pico cell communication system.
2. Discussion of Related Art
Wireless communication systems are expected to develop from a second generation wireless communication system for voice and character transmission to a third generation wireless communication system of an International mobile telecommunication-2000 (IMT-2000) for image information transmission and to a fourth generation wireless communication system with a transfer rate of 100 Mbps or more. Such a fourth generation broadband wireless communication system is expected to use a millimeterwave, not a conventional frequency band that is already in a saturation state.
In the development of the millimeterwave wireless communication system, the most significant concerns are miniaturization and low price. In the development of the conventional wireless communication system, one of factors making it most difficult to achieve the miniaturization and the low price is just a filter. In particular, a waveguide filter occupies a basic area depending on a frequency in air, and should use flange or transition of a variety of formats depending on a transmission format of input/output.
Accordingly, the conventional waveguide filter has a drawback in that an occupation area is considerably great in the whole wireless communication system, and a high cost is required for device manufacture.
As a prior art for solving the conventional drawbacks, U.S. Pat. No. 6,535,083 discloses “EMBEDDED RIDGE WAVEGUIDE FILTERS.” In the U.S. Pat. No. 6,535,083, as shown in FIG. 1, both sidewalls of a dielectric waveguide resonator are implemented using each one line of vias 20 disposed in multi-layered dielectric layers 11, 13, and 14 and ground planes 10 and 12 on a top and a bottom of the dielectric layers. Ridge waveguide portions 161, 162, and 163 are implemented using vias 18 and patterns 301, 302, 303, 321, 322, and 323. Further, input/output ports 22 and 24 of strip lines 26 and 28 connected to a conductor by coupling units 27 and 29 through the pattern are implemented on low temperature cofired ceramic (LTCC), high temperature cofired ceramic (HTCC), and print wired board (PWB) substrates.
However, the U.S. Pat. No. 6,535,083 has a drawback of being improper to a present process in which the vias should be maintained at predetermined intervals according to a design rule, and has a drawback of being incapable of controlling a height of a dielectric waveguide as desired, and has a drawback in that another transition should be necessarily used for connection with and measurement of other external devices since input/output lines should be within a multi-layered substrate.
Further, as another prior art for solving the conventional drawbacks, there is an article entitled “A V-band Planar Narrow Bandpass Filter Using a New Type Integrated Waveguide Transition”, announced in IEEE Microwave and Wireless Components letter on December 2004 by Sung Tae Choi. As shown in FIG. 2A, the article discloses a dielectric waveguide filter for a small size, a low insertion loss, and broadband spurious suppression. Further, on a two-dimension plane are implemented Grounded CoPlanar Waveguide (GCPW) input/output ports, an impedance matching portion, a T-type waveguide-GCPW signal converter, and a dielectric waveguide resonator. However, the conventional art has a drawback of being incapable of implementing an attenuation pole for removing an image wave at a top or bottom of a pass band.
Further, as yet another prior art for solving the conventional drawbacks, there is an article entitled “60 GHz band Dielectric Waveguide Filters with Cross-coupling for Flip chip Modules” announced in IEEE-S Digest, p 1789-1792 on June 2002 by Masaharu Ito. As shown in FIG. 2B, the article discloses a cross-coupling dielectric waveguide filter for a small size, a low insertion loss, and broadband spurious suppression, and with an attenuation pole for removing an image wave at a top of a pass band. On a two-dimension plane are embodied CoPlanar Waveguide (CPW) input/output ports, a U-type waveguide-CPW signal converter, and a dielectric waveguide resonator. However, the prior art has a drawback of being difficult to implement cross-coupling for removing the image wave at the bottom of the pass band.